Punishment using positive and negative reinforcement can be very effective. If someone does something wrong, you want to set them a task that will help them make better decisions next time. To do that, you have to work out consequences. The best example I have is from my days of substituting kids who were in detention. When they first arrived, they had to write a paper outlining what they did and how they would avoid doing it again. It was amazing how many times it took them to honestly say what they did (without blaming others or circumstances) and to develop a plan for the future. It worked because there were no excuses.